A major problem with conventional systems for cooling the gas leaving the coal gasification reactor is the high concentration of molten ash in the product or synthesis gas exiting the reactor. Deposition of molten ash on heat exchanging surfaces downstream of the reactor must be avoided because the deposition would adversely affect heat transfer and pressure drop through the heat exchange section. Furthermore, since different coals produce ashes having different characteristic properties with respect to deposition on heat exchanging surfaces, designing a heat exchange section that will not foul for a range of coal types becomes more difficult.
Conventional coal gasification schemes for cooling the product gas leaving the reactor employ a radiation zone in communication with a water-containing bath whereby combustion residues are captured by the bath as disclosed in U. S. Pat. Nos. 4,310,333 and 4,520,760. 4,270,493 discloses a radiant cooler wherein molten ash particles which are entrained in the produce gas coalesce and precipitate out of the gas stream.
The present invention is directed to overcoming the problem of molten ash depositing on heat exchanging surfaces.
Applicants are not aware of any prior art which, in their judgment as persons skilled in this particular art, would anticipate or render obvious the present invention.